fix: React agent should be able to work with provided config (#146)

passing a custom_config was failing 
```
python -m examples.agents.react_agent
```

---------

Co-authored-by: Hardik Shah <hjshah@fb.com>

Author: hardikjshah

src/llama_stack_client/lib/agents/agent.py

@@ -3,12 +3,15 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
+import uuid
+from datetime import datetime
 from typing import Iterator, List, Optional, Tuple, Union
 
 from llama_stack_client import LlamaStackClient
+
 from llama_stack_client.types import ToolResponseMessage, UserMessage
 from llama_stack_client.types.agent_create_params import AgentConfig
-from llama_stack_client.types.agents.turn import Turn
+from llama_stack_client.types.agents.turn import CompletionMessage, Turn
 from llama_stack_client.types.agents.turn_create_params import Document, Toolgroup
 from llama_stack_client.types.agents.turn_create_response import (
     AgentTurnResponseStreamChunk,
@@ -18,14 +21,12 @@
     AgentTurnResponseStepCompletePayload,
 )
 from llama_stack_client.types.shared.tool_call import ToolCall
-from llama_stack_client.types.agents.turn import CompletionMessage
-from .client_tool import ClientTool
-from .tool_parser import ToolParser
-from datetime import datetime
-import uuid
 from llama_stack_client.types.tool_execution_step import ToolExecutionStep
 from llama_stack_client.types.tool_response import ToolResponse
 
+from .client_tool import ClientTool
+from .tool_parser import ToolParser
+
 DEFAULT_MAX_ITER = 10
 
 
@@ -55,7 +56,7 @@ def _create_agent(self, agent_config: AgentConfig) -> int:
         self.agent_id = agentic_system_create_response.agent_id
         return self.agent_id
 
-    def create_session(self, session_name: str) -> int:
+    def create_session(self, session_name: str) -> str:
         agentic_system_create_session_response = self.client.agents.session.create(
             agent_id=self.agent_id,
             session_name=session_name,

src/llama_stack_client/lib/agents/client_tool.py

@@ -4,10 +4,19 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+import inspect
 import json
 from abc import abstractmethod
-from typing import Callable, Dict, TypeVar, get_type_hints, Union, get_origin, get_args, List
-import inspect
+from typing import (
+    Callable,
+    Dict,
+    get_args,
+    get_origin,
+    get_type_hints,
+    List,
+    TypeVar,
+    Union,
+)
 
 from llama_stack_client.types import Message, ToolResponseMessage
 from llama_stack_client.types.tool_def_param import Parameter, ToolDefParam
@@ -155,9 +164,10 @@ def get_params_definition(self) -> Dict[str, Parameter]:
                     name=name,
                     description=param_doc or f"Parameter {name}",
                     parameter_type=type_hint.__name__,
-                    default=param.default if param.default != inspect.Parameter.empty else None,
+                    default=(param.default if param.default != inspect.Parameter.empty else None),
                     required=is_required,
                 )
+
             return params
 
         def run_impl(self, **kwargs):

src/llama_stack_client/lib/agents/react/agent.py

@@ -3,17 +3,18 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
+from typing import Any, Dict, Optional, Tuple
+
+from llama_stack_client import LlamaStackClient
+from llama_stack_client.types.agent_create_params import AgentConfig
 from pydantic import BaseModel
-from typing import Dict, Any
+
 from ..agent import Agent
-from .tool_parser import ReActToolParser
+from ..client_tool import ClientTool
 from ..tool_parser import ToolParser
 from .prompts import DEFAULT_REACT_AGENT_SYSTEM_PROMPT_TEMPLATE
 
-from typing import Tuple, Optional
-from llama_stack_client import LlamaStackClient
-from ..client_tool import ClientTool
-from llama_stack_client.types.agent_create_params import AgentConfig
+from .tool_parser import ReActToolParser
 
 
 class Action(BaseModel):
@@ -92,6 +93,8 @@ def get_tool_defs():
                 output_shields=[],
                 enable_session_persistence=False,
             )
+        else:
+            agent_config = custom_agent_config
 
         if json_response_format:
             agent_config.response_format = {